Control system



H. 0. JAMES. CONTROL SYSTEMJ" APPLICATION FILED JUL 81 19:19.

Patntedsept. 27,1921.

WITNESSES": 62. W

INVENTOR Hang/Z2 Jamar BY ATTdRNEY UNITED STATES PATENT OFFICE.

HENRY D. JAMES, OF EIlGEWOOD PARK, PENNSYLVANIA, ASSIGNOR TO WESTING-.HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL-VANIA.

con'rnor. SYSTEM.

T 0 all whom it may concern:

Be it known that I, HENRY D. JAMES, a citizen of the United States,,anda resident of Edgewood Park, in the county of Allegheny and State ofPennsylvania, haveinvented a new and useful Improvement in ControlSystems, of which the following is aspecification. 1

My invention relates to control systems of general application but moreparticularly to motor-control systems of the type illustrated anddescribed in my copending application Serial No. 236,937, filed May 27,1918, 1n which a plurality of contactors for short-' circuiting theaccelerating resistor are adapted to be closed by relays which are, inturn,

controlled by'an energizing coil in parallel circuitwith the resistor.

As the energizing coil becomes short-circuited, and, therefore,ineffective, upon the short-circuiting of the resistor, some means mustbe provided for maintaining the re sistor-short-lcircuiting contactorsclosed. In the said copending application, I effect this result with theaid of an additional coil.

' An object of my presentinvention is to provide an improvedmotor-accelerating system of the above-described character which shalldispense with the additional coil.

One method of preventing connecting the motor; directly across the linewithout the accelerating resistor iii-circuit with the motor armature,upon the motor being stopped and immediatelyrestarted, or after voltagefailure andthe return of voltage to the line, is toprovide forpreventing the-closing of the motorcircuit until the. resistor-short-icircuiting contactors all occupy their open positions. In theabove-mentioned application and in another copending application, SerialNo. 249,344, filed August 10,1918, 1* have illustrated several ways ofattaining this result.

A second object of my invention is to provi'dea novel acceleratingsystem for. accomplishing the above-mentioned result in a new andimproved way. r Other and further objects of my inventio will appearhereinafter.

According to the present invention, the actuating coil ofthe linecon-tactor is adapted to beenergized by a circuit'comprising a switchthat is mechanically connected to the relay which controls the firstcontactor to.close.-* I This relay is shunted by a resistorSpecification of Letters Patent. Patented Sept, 27, 1921 Applicationfiled January 8, 1919. Serial No. 270,148.

of high resistance which reduces the current traversing the linecontactor coil so as to prevent the actuation of the line contactor whenthe mechanically connected switch is open, though allowing sufficientcurrent to flow through the coil to maintain the contactor closed, whenthe mechanically connected switch is closed. The energizing coil, whichis connected in parallel circuit with the accelerating resistor, isadapted to be maintained energized afterthe resistor has becomeshort-circuited by connecting it, in circuit with a second resistor ofhigh resistance, across the line. i I In the accompanying drawings,Figure 1 is a diagrammaticview of a control system, arranged accordingto my invention, for accelerating a motor. Figs. 2 and 3 are,respectively, a side and an end elevation of a preferred switch employedin connection with the system-of Fig. 1.

Referring to Fig. 1, a motor, the armature of which is shown at 1 andthe shunt field'- magnet winding at 2, is connected between,

line conductors 3 and 4, separated by a line contactor 5, with anaccelerating resistor 6' tact witha contact member 9. One or morecontactors 10, 11 and 12 (three are. illustrated) control the shuntingof successive portions 13, 14 and 15 of the accelerating resistor 6through the medium of energizing coils 19, 20 and 21, which energizationis effected by the controller arm 7 making contact with contact members'16, 17 and 18, respectively. A coil'22 is connected, at '7 9 and, 80,through the contactor 12 in its in operative position, a'protectiveresistor 60, the contact member9 and the controller arm 7, by way of aconductor 28, in parallel circuit with the terminals of the resistor 6.Th energizationof the coil 22, as explained below, causes the successiveclosing of relays 25, 26 and 27 in accordance with the strength of thecurrent passing'through the coil 22. The coil 19 and the relay 25 areseries-connected in a. circuit. extending from the line conductor3,through the point 80, by way of the conductor28, through the controllerarm 7? and the contact member 16, to the line parallel relation to thecoil 19 and the relay 25. The relay 26 and the contactor 10, and therelay 27 and the contactor 11, are mechanically interlocked at 55 and56. The relay 25 engages a contact member 56, in its open position,which controls the circuit of the coil 8. This contact member may becontrolled by the armature 32, as is mentioned below. A resistor 59 ofhigh resistance is adapted to be connected across the line in circuitwith the coil 8 upon the closing of the relay 25 and the consequentdisengagement of the contact member-56, the contact members 56 and ofthe relay 25 being shunted by the resistor 59. After the resistor 6- hasbecome short-circuited, the above-described circuit of the coil 22 isopened by the contactor 12, but this coil is maintained energized byline voltage through a resistor 61 of high resistance.

The relays 25, 26 and 27 are preferably of the type constitutingthesubje'ct-matter of a copending application, Serial No. 241,259, filedJune 21, 1918, by De Camp, and assigned to the YVestinghouse Electric &Manufacturing Co. The device is illustrated in Figs; 2 and 3. Aninsulating panel 29' carries two brackets 30 and31 for supporting thecoil 22' which, when energized by the current flowing through it,creates a magnetic field for attracting an armature 32 and any desirednumber (three are illustrated) of additional armatures 33. A compressionspring 36 is adjustably mounted upon a non-magnetizable rod 3(, slidablymounted in projections 38 and 39 which are rigidly connected to, or areintegral parts of, the bracket 31. The projections 38 and 39 serve alsoas pole pieces for the armatures 32 and 33, respectively. A bar 40-isrigidly connected to the rod 37 and normally engages the armatures 33.The spring 36 thus normally maintains the armatures 33 in open position,with the members 41, which are carried by these armatures, in contactwith the pole piece 39. The members 41 are, preferably, ofnon-magnetizable material to prevent freezing.

The'armature 32' is provided with brackets 42, which are pivotallymounted upon the bracket 30, and is normally retained inthe broken-lineposition of Fig. 2 'by a weak spring 43. The bracket 30 supports also anon-magnetizable U-shaped member 44 between the arms of which arepivotally mounted the armatures 33' which carry'the movable contactmembers 45,46 and 47 of the relays 25, 26 and 27, shown in Figs. 2 and 3as closed. The stationary contact members 48, 49 and 50 of'the relays25, 26 and 27 are mounted upon the insulating panel 29. Springs 51 areattached to lon gitudinally adjustable members 52 and to the other endsof the members 41. The pole piece 39 is provided with longitudinallyadjustable members 53 to regulate air gaps between these members and thecorresponding armatures. By means of this adjustment or by means of themembers 52, the action of the magnetic flux produced by the coil 22 maybe so regulated that the armatures 33 will be operated in the propersequence. The contact member 45 is adapted to cotiperatewith theadditional contact member 56 in the open position of the armature 33. Ifdesired, this contact member 56 may be replaced by a contact memberwhich is adapted to be closed by the armature 32 when this armatureoccupies its open position, as illustrated and described in the abovereferred to application by De Camp.

The operation is as follows: upon the actuation of the controller arm 7a to the position a, the coil 8 is energized by a circuit extending fromthe line conductor 3, through the point 80, the conductor 28, thecontroller arm 7, the contact member 9, the coil 8 and the contactmembers 56 and 45, to the line conductor 4. The contact member 56 may beone like that illustrated in Fig. 2, or one controlled by the armature32 in its open position. The circuit including.

the resistor 59 is not sufficiently energized to cause the closing ofthe contactor 5, but will maintain this contactor closed once it hasbecome closed by the energization of the above-described circuitcomprising the con tact members 45 and 56. 'Upon the closing of thecontactor 5, the motor circuit is completed, current flowing through theresistor 6 and the armature 1, and also through the shunt field-magnetwinding 2. Current is also shunted across the resistor 6 between thepoints 79 and 80 through the coil ,22. The energization of the coil 22creates a magnetic field which attracts the armature 32 to the polepiece 38, as illustrated in the full-line position at 32. The rod 37 isthereupon pressed inwardly, in opposition to the force of the spring 36,forcing the bar 40 away from thearmatures 33. The movement'of thearmature 32 is from the brokenline to the full-line position of Fig. 2.The

flux of the magnetic field will overcome the forces of the springs 51,and the armatures 33 will remain with the stops 41 in engagement withthe pole piece 39. As the motor accelerates and the current begins todie down, the magnetic flux set up by the coil 22 becomes weakenedJAfter a time, when the flux has decreased to a predetermined value, thespring 51, attached to the armature 33 of the relay 25, will overcomethe flux of this field so that :the relay 25 will be closed. The timewhen this operation occurs depends upon the air gap 70 and the tensionof the spring 51. The relays 26 and 27, however, will remain open. Theclosing of the relay 25, of course,opens the contact members 45 and. 56but the contactor 5 remains closed because the circuitiof the coil 8remains energized, as above de cribed, by the circuit'includingtheresistorfl59;

The controllerarm "7. may be actuated through positions a, and c to theposition d in one step or it'ma'yl be actuated step-bystep. Thedescription of the operation is based-upon the supposition that thecontroller arm Tfihas been" actuated to the position (Z in one step soas to'per'mit'gthe auto matic operation ofthe relays andgcontac tors asdescribed below. w

Upon the closing. of the relay 25, the above-described circuit ofthefjcoil 19 and the relay 25 becomesclosed through the contact member16 and'the controller arm 7 to cause the energization of the coil 19 andthe consequent closing of the contactor 10 which, in turn, creates ashunt path for the portion 13 of the resistor 6. The motor then furtheraccelerates to decrease the voltage across the terminals of the coil 22and thus weaken the magnetic field in the neighborhood of this coil,which permits the closing of the relay 26. A circuit is thus com pletedfrom the point 80, which is connected to the line conductor 3, by way ofthe conductor 28, through the controller arm 7, the contact member 17,the coil 20 and the relay 26, to the line conductor 4. Thecoil 20, thusbecoming energized, causes theclosing of the contactor 11 and theshunting of the resistor portion 14. After the motor has furtheraccelerated, the magnetic field surrounding the coil 22 is againweakened and the relay 27 is closed, creating a circuit for the coil 21through the controller arm 7 a and the contact member 18. is thereuponclosed to short-circuit the resistor portion 15, thereby effecting theconnection of the armature 1 directly across the line.

The shunting of the resistor portion 15 by thecontactor 12 effects theopening of the circuit of the coil 22, tending to release the armature32 and to open the relays 25, 26 and 27. I prevent this, in'thepresentsystem, by connecting the coil 22 across the lineconductors 3 and 4 uponthe closing of the contactor 12, the circuit extending from the point80, which is connected to the line conductor 3, through thecontrollerarm 7, the contact member 9, the coil 22 and the resistor 61,to the line conductor 4. The coil 22 thus remains sufficiently energizedto maintain the armature 32 in the illustratcd position (Fig. 2) and,therefore, to maintain the resistor 6 short-circuited.

If the controller arm 7 be returned to the off position, causing theopening of the contactors 10, 11 and 12, and the controller arm 7 bethen immediately returned to the position (Z, or if, after a failure ofline voltage, energy is restored to the line, there will be danger,since the coil 22 may maintain The contactor 12 the armature 32 in thefull-line, actuated position (Fig. 2 ,of causing the immediatereclo'sing of the contactors 1'0, 11 and 12, as described in my,above-mentioned copending applications, and the "consequent prematureconnecting of the armaturel directly across the line conductors 3 and 4without protective resistance inseries therewith. I may prevent thisundesirable effect by means of the mechanical interlocks 55 and 57 forin suring the sequential operation of the relays 25, 26 and 27' and thecontact memberslO, 11 and. 12, or I may prevent this result electrically. "In the present system, it will be noted, the coil 22 may beinitially energized only when the contactor 12 occupies its openposition. I

Although I have described my system as employing a particular relaydevice, it will be understood that other relays, and particularly thoseof the ordinary type, may be employed. It will be understood also thatother changes may be made without departing from the spirit of myinvention, the scope of which is set forth in the appended claims.

I claim as my invention:

1. The combination with an electric motor and a pair of controllingswitches therefor, each of said switches having a controlling magnetcoil, one of said switches being normally biased to an open position, of

means for effecting the simultaneous energization of said coils and theclosing of the other of said switches only when said one switch is inits open position, and a circuit, including a resistor, controlled bysaid one switch for maintaining said other closed upon the closing ofsaid one switch.

2. The combination with an electric motor having a resistor, a switchfor closing the circuit of said motor and having an actuating coil, aswitch for controlling said resistor and having a controlling coil inparallel circuit with said resistor and a switch mechanically connectedto said controlling switch, of a pair of auxiliary resistors, means forclosing the circuit of said actuating coil through said mechanicallyconnected switchand through one of said auxiliary resistors, and meansfor connecting said controlling coil in circuit with said otherauxiliary resistor upon the short-circuiting of said first-namedresistor.

3. The combination with an electric motor having a resistor, a source ofenergy for said motor, a switch for connecting said motor to said sourceand having an actuat- &

ing coil when said one short-circuiting switch occupies said oneposition, means for actuating said one switch, means for maintainingsaid actuating coil energized, and means for energizing saidparallel-connected .coil from said source.

4:. The combination with an electric motor having a resistor associatedtherewith, a source of energy for said motor, a switch for connectingsaid motor to said source and having an actuating coil, a plurality ofcontactors for short-circuiting said resistor, a relay for each of saidcontactors, means for maintaining said relays open, and a coil inparallel circuit with said resistor for overcoming said maintainingmeans and for maintaining said relay open, of a switch mechanicallyconnected to the first of said relays to-close for connecting saidactuating coils to said source, a circuit comprising an auxiliaryresistor in parallel relation to said first relay for maintaining. saidactuating coil energized at reduced voltage from said source means forsuccessively closing said relays to cause the closing of the respectivecontaotors, and a circuit comprising a second auxiliary resistor formaintaining said parallel-connected coil energized at a reduced voltagefrom said source.

In testimony whereof I have hereunto subscribed my name this'21st day ofDec.-, 1918.

HENRY D. JAMES.

